GOODWILL AND INTANGIBLE ASSETS (Schedule of Goodwill) (Details) - USD ($) $ in Thousands	6 Months Ended
	Oct. 31, 2020	Oct. 31, 2019
Goodwill [Roll Forward]
Goodwill before impairment losses, beginning balance	$ 850,435	$ 552,234
Accumulated impairment losses, beginning balance	(138,297)	(32,297)
Goodwill, beginning balance	712,138	519,937
Acquisitions	2,214	8,491
Disposals and foreign currency changes, net	13,131	(2,589)
Impairments	0	0
Goodwill before impairment losses, ending balance	865,780	847,628
Accumulated impairment losses, ending balance	(138,297)	(32,297)
Goodwill, ending balance	$ 727,483	815,331
Wave
Goodwill [Roll Forward]
Acquisitions		$ 289,492